THE MICROSCOPE IN ZOOLOGY. 91 



lacuna, their disposition in regard to each other and 

 to the Haversian canals, and the number and course 

 of the canaliculi, the nature of even a minute fragment 

 of bone may often be determined with a considerable 

 approach to certainty, as is shown by the following 

 examples, among many which might be cited Dr. Fal- 

 coner, the distinguished investigator of the fossil re- 

 mains of the Himalayan region, and the discoverer of 

 the gigantic fossil tortoise of the Sivalik hills, having 

 met with certain small bones about which he was doubt- 

 ful, placed them in the hands of Professor Quekett 

 for minute examination; and was informed, on micro- 

 scopic evidence, that they might certainly be pronounced 

 reptilian, and probably belonged to an animal of the 

 tortoise tribe ; and this determination was fully borne 

 out by the evidence, which led Dr. Falconer to con- 

 clude they were toe-bones of his great tortoise. Some 

 fragments of bone were found some years since in a 

 chalk-pit, which were considered by Professor Owen 

 to have formed part of the wing-bones of a long- 

 winged sea-bird allied to the albatross. This deter- 

 mination, founded solely on consideration derived 

 from the very imperfectly preserved external forms of 

 these fragments, was called in question by some other 

 palaeontologists, who thought it more probable that 

 these bones belonged to a large species of the extinct 

 genus Pterodactylus, a flying lizard, whose wing was 

 extended upon a single immensely prolonged digit. 

 No species of Pterodactyle, however, at all comparable 

 to this in dimensions was at that time known ; and the 

 characters furnished by the configuration of the bones 

 not being in any degree decisive, the question would 

 have long remained unsettled, had not an appeal been 

 made to the microscopic test. This appeal was so 

 decisive by showing that the minute structure of the 

 bone in question corresponded exactly with that of 



